As a flat panel type radiation detector (FPD) developed for a digital radiographic image technique which can acquire directly a digital radiographic image, there are two types of methods. One of them is a scintillator method in which a radiation is converted to a visible light with a phosphor such as Gd2O2S or CsI, then the visible light is converted into an electric charge with a photodiode. Another is a method in which X-rays are directly converted into an electric charge with an X-ray detection element represented by a Se detector.
As a flat panel detector of a scintillator method, it is known, for example, a flat panel type radiation detector (FPD) which is made of a scintillator panel having a phosphor layer; and a photoelectric conversion element containing a thin film transistor (TFT) combined with a charge coupled device (CCD), as described in Japanese Patent Application Publication (JP-A) No. 2005-114456.
The above-described FPD using a scintillator panel having a phosphor layer has been widely used in recent years for a nondestructive examination in the industrial filed or for an application to a dental use which collects still images by introducing in an oral cavity.
In these applications, it is required diversification of magnitude and forms of device. For example, in the application for a dental diagnosis filed, it is required a small device used for an oral cavity, and a variety of forms used for panoramic radiography or cephalic radiography.
And for a small device, it is required to a detector having a large effective image taking region. Moreover, for diversification of form, it is required to efficiently produce scintillator panels of various sizes with relatively small size in the production step.
As a phosphor used for a phosphor layer of a scintillator provided with a phosphor layer, it is advantageously used a phosphor composed of cesium iodide (CsI) as a mother body and an activator contained therein from the viewpoint of conversion efficiency from X-rays to a visible light.
Since a phosphor layer used with a phosphor composed of cesium iodide (CsI) as a mother body and an activator contained therein has a deliquescent property and easily damaged, it will be relatively easily deteriorated with age. Therefore, usually, a protective layer is provided on the phosphor layer for use.
As a method far preparing a protective layer for use, there is disclosed a method in which an upper portion and a lateral face portion of a phosphor layer and an outer peripheral portion of the support are covered with a polyparaxylylene resin (for example, refer to JP-A No. 2004-105518). Another known method is a method in which at least the opposite side of the scintillator panel facing the support and the lateral shoe of the scintillator panel are covered with a transparent resin film having a water transmissivity of less than 1.2 g/m2 per a day.
Moreover, the following method are known; a technology of covering the whole surface of the support including the scintillator portion with polyparaxylylene as disclosed in JP-A No. 2002-116258; a technology of providing unevenness to the support so as to prevent polyparaxylylene floor peeling of as disclosed in JP-A No. 2005-338067; and a technology of fusing the edge portion of the phosphor so that the edge portion of the phosphor may not damage the inner portion of the film when the substrate is a transparent resin film as described in JP-A No. 2008-139291.
Moreover, in order to improve protection ability, therein known a method of vapor-depositing the material of a phosphor layer under the condition of supporting the substrate to be formed with a scintillator layer thereon at three or more very small points (refer to Patent document 1).
However, by using the above-described conventionally known methods, there are problems of insufficient optically effective area or low production efficiency when it is intended to produce a small-sized device, and a relatively small-sized device of various sizes.
Patent document 1: JP-A No. 2006-38870